This invention generally relates to the art of electrical connectors and, more particularly, to a terminal module for connection to a signal cable having a ground member.
In high speed data communications, many electronic devices rely upon transmission lines to transmit signals between related devices or peripheral devices and circuit boards of a computer, for instance. These transmission lines incorporate signal cables that are capable of high-speed data transmissions. A typical signal cable may use what are known as one or more twisted pairs of signal wires that are twisted together along the length of the cable. One or more grounding drain wires also may be twisted along with the signal wires. The wires may be encircled by an associated grounding shield, such as a metal braided tube, either with or without the drain wires. The signal wires typically are encased by an insulating covering, and the entire cable typically is encased by an outer insulating sheath.
In order to maintain electrical performance integrity from such a transmission line or cable to the circuitry of an associated electronic device, it is desirable to obtain a substantially constant impedance from the transmission line to the circuitry to avoid large changes in the impedance. Problems in controlling the impedance of a connector at a connector mating interface is well known, because the impedance of a conventional connector typically changes through the connector and across the interface of two mating connector components. The signal strength is reduced across a connector interface presenting changes in impedance and some of the signal is reflected back to the signal source.
Twisted wire cable is designed to maintain a desired impedance through an electrical transmission line, and this is accomplished by maintaining a constant geometry or physical arrangement of the signal conductors, the drain wires and/or the grounding shield. Unfortunately, an impedance drop usually is encountered in the termination area where the cable is terminated to a connector. This occurs when the signal conductors of a twisted pair are untwisted, oriented to mate with the termination portions of the cable connector and soldered thereto. It, therefore, is desirable to maintain a desired impedance as constant as possible throughout the connector and its termination to the cable. This is termed xe2x80x9cimpedance matchingxe2x80x9d in the connector arts.
When a signal cable is terminated to a connector, the twisted wires are untwisted and the braided shield surrounding the wire pairs may be peeled back and at least partially unbraided. This is done manually and it often results in moving the signal wires, the drain wires and/or the grounding shield out of their original geometry in which they exist in the cable. This introduces variability into the electrical performance. This rearrangement may lead to a decoupling of the ground and signal wires from their original state and it often results in an increase of impedance of the electrical assembly in the cable-connector termination area as compared to that of the cable. This increase in impedance may exceed the tolerances designed for the connector system and lead to large impedance discontinuities for the system, which will deleteriously impact the electrical performance of the system. This variability and rearrangement changes the physical characteristics of the system in the termination area, resulting in problems caused by an undesirable change in the impedance of the system through the connector interface.
The present invention is therefore directed to a unique termination structure for terminating the cable conductors at termination section of a cable connector.
A general object of the present invention is to provide a new and improved electrical connector for terminating to an end of a cable having at least one pair of signal wires and an associated ground.
Another object of the present invention is to provide a termination assembly for terminating a single or multiple signal channel transmission cable to a plug connector, in which the transmission cable includes at least one pair of differential signal wires, each such pair having a ground associated therewith, and the termination assembly including a ground terminal having a termination portion that extends rearwardly of an insulative housing thereof, the termination portion including a signal wire platform and a conductive retainer that engages the platform in a manner so as to retain the free ends of the signal cable and its two associated differential signal wires in a particular position within the termination assembly.
A further object of the present invention is to provide an improved termination assembly for use in terminating differential signal wires to a connector wherein the termination assembly includes an insulative housing and a plurality of conductive terminals supported thereby, at least two of the terminals being adapted for respective termination to the differential signal wires and another of the terminals being a ground termination terminal for engaging a ground associated with the differential signal wires, the termination assembly further including a conductive retainer that engages and extends over the ground terminal, the ground terminal termination portion and the retainer cooperatively defining a conductive enclosure that encompasses a free end of the signal cable from which the signal wires and ground extend, the retainer and the termination portion orienting the ground members in a fixed position with respect to the differential signal wires.
Yet a still further object of the present invention is to provide a means for orienting the ground wires of a signal cable containing two differential signal wires therein, the orienting means including openings formed in both the ground terminal termination portion and the retainer member, the openings being aligned with each other and providing shoulders against which the signal cable ground wires may be folded and soldered to the termination assembly, the openings being aligned with each other vertically so as to maintain the ground wires in a preselected arrangement with respect to each other and with respect to the differential signal wires.
These and other objects of the present invention are accomplished by way of the novel unique structure thereof.
In the exemplary embodiment of the invention, a plug-style connector is provided with an insulative housing having a mating end and a terminating end. A pair of signal terminals are supported by the housing and have contact portions disposed proximate to the mating end thereof and termination portions disposed proximate to the terminating end for termination to the pair of signal wires. The housing also includes a ground terminal having a contact portion disposed proximate to the mating end thereof and a termination portion disposed proximate to the terminating end for termination to the ground member. A signal cable retention clip is provided independent of the ground terminal and is structured so as ro engage and cooperate with the ground terminal termination portion thereof to clamp the cable therebetween and facilitate orientation of the signal wires and ground member of the cable.
According to one aspect of the present invention, the retention clip acts as a conductive retainer that is formed of conductive material and which combines with the ground terminal to form a shield about the free end of the signal cable, which has its outer insulating sheath cut-off to expose the cable""s ground members and signal wires. The shield formed by the retainer clip and the ground terminal termination portion extends beyond the distal end of the sheath. The clip may further include deformable crimp portions that engage with the termination portion of the ground terminal so that the clip and the ground terminal termination portion cooperatively define both a conductive enclosure for the open end of the signal cable and a clamp about the distal end of the sheath of the cable to provide strain relief between the cable and the connector. The clip and the terminal cooperatively define a ground enclosure that encompasses the signal cable and extends over the entire circumference of the signal cable
In another aspect of the present invention, the ground members of the signal cable may take the form of a pair of drain wires each, of which is associated with one of the two signal wires. The ground terminal termination portion and the retainer clip include means for locating the drain wires in a preselected orientation and also serve to maintain the drain wires in a particular orientation with respect to the signal wires that generally follows the original orientation that the drain wires exist in the cable. This locating means is provided by a hole, or slot, formed in the termination portion and retainer clip through which the drain wires may be inserted and bent over the outside thereof and over the free end of the signal cable with this configuration each bent drain wire has a metal surface upon which it may be soldered.
Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings.